Scientists have discovered how a woman’s brain changes when she has a second child

It’s estimated that around 210million pregnancies occur worldwide each year.

And it’s no secret that the experience of carrying a child and giving birth has a massive impact on a woman’s body – changing everything from hormone levels and breast size to hair texture and teeth.

But until recently, there’s been one aspect of pregnancy that’s remained somewhat unclear – and that’s the impact on the brain if you have more than one child.

Scientists from the Amsterdam University Medical Center discovered in 2016 that a first pregnancy changes a woman’s brain structure and resting-state brain activity, and now some light has been shed on what happens during a second pregnancy.

brain

This is thanks to the BeMother project, which scanned the brains of hundreds of women, including 127 pregnant women – some expecting their first child and some expecting their second. 

Researchers carried out multiple MRI scans on the participants before conception, during pregnancy, and six months postpartum to build a comprehensive picture of the brain and activity, to see how it changed over time.

And the findings revealed that structural and functional changes occur in the brain with each pregnancy, but in unique ways.

The changes are more pronounced during a first pregnancy, when grey matter, the information-processing tissue of the brain and central nervous system, decreases by an average of nearly 5 per cent.

The grey matter is reduced mostly in the default mode network of the brain, which is the area responsible for daydreaming, recalling memories, planning the future, and reflecting on yourself.

But before you panic, this decrease doesn’t mean the brain is damaged or that the person has become less intelligent.

Instead, experts think it is a form of ‘synaptic pruning’, with lesser-used connections removed to strengthen ones that are needed, to make the brain more ‘efficient’ for motherhood. 

‘I like to use the metaphor of pruning a tree. Some of the branches are cut to make it grow more efficiently,’ Prof Susana Carmona, a co-lead of the study, explained to the BBC.

‘We find in biology, as in life, sometimes less is more.’

Around 3.4 per cent of the lost grey matter is regained six months following birth, but not all of it fully returns.

What’s perhaps most interesting from the research, though, is what happens during a second pregnancy.

The changes are not simply repeated – they are built upon.

The regions that were changed the first time showed only modest differences the second time, suggesting the groundwork had already been laid for motherhood and simply needed to be ‘fine-tuned’ for a second child.

However, a few further adaptations are made in the brain, with the most notable occurring in the networks responsible for attention and responsiveness – likely because of the additional focus needed to care for multiple children.

Researchers added that a second pregnancy ‘uniquely changes’ a woman’s brain, and that the timing of the changes is different for each pregnancy.

For first-time mothers, the changes are more obvious after giving birth, but for a woman having a second child, the changes are more apparent while she is pregnant.

The study also suggests a link between changes in the brain and bonding with a child, as those who had experienced greater changes were more likely to report bonding well with their babies.

Despite these findings, Carmona says much more work is still required to build a detailed neurological map of the pregnant brain and chart how it transforms as a woman becomes a mother.

She hopes further research will improve our understanding of pregnancy-related brain changes and ultimately reveal more about mental health conditions such as postpartum depression.